Have you ever heard that you can freeze olive oil to see if it's real? Recently, we received a reader question asking “Should all olive oil freeze (or harden) in the refrigerator? A comment was made on the Dr. Oz show stating that, if it does not freeze, it has been altered. My extra virgin oil stayed liquid in the refrigerator.”

To answer this question, we reached out to Dr. Selina Wang, Research Director at the UC Davis Olive Center.

Dr. Wang: Based upon our analysis, we find that the “fridge test" is unreliable in detecting either purity or quality. For more information about our "fridge test," please read our response to Dr. Oz's show here.

Is it true that olive oil is commonly diluted with less expensive oils?

Dr. Wang: In our research studies, which you can find on the University of California's Olive Center website, we did find some food service oils were adulterated with soybean/canola oil. At the supermarket, we found that about 65% extra virgin olive oil (EVOO) did not meet the EVOO standards. This may be due to the fact these oils were old (though well before the best-before-date) or they were adulterated with cheap refined olive oils.

How should olive oil be stored? How long does it last before it goes bad?

Dr. Wang: Oils should be stored in a dark bottle, in a cool and dark place. In general, a brand new oil has about 1.5 to 2 years of shelf life. Once the bottle is open, it should be used up within 6 months.

Is it OK to cook with olive oil? Or should it just be used cold for salad dressings, etc.?

Dr. Wang: Unlike what most people believe, fresh olive oil has a high enough smoke point for cooking.

What are some of the benefits of olive oil vs. vegetable oil vs. canola oil vs. corn oil or other kinds or oil? When should you use each oil?

Dr. Wang: Compared to the other oils you've listed, extra virgin olive oil is the only un-refined oil. This means it still contains all the natural antioxidants. Each of these oils also has a different fatty acid profile; olive oil is high in mono-unsaturated fat, which is good for us.

Who determines what’s for dinner at your house?

I decide – It guarantees I get what I’m craving!I decide – It ensures a nutritious meal.The kids decide – I have to cook what they’ll eat.We decide as a family – Teamwork is best.We each pick out our own – We live to eat out.Whoever is cooking decides.